In our previous paper, we have proposed a new algorithm to calculate the power spectrum of the curvature perturbations generated in inflationary universe with use of the stochastic approach. Since this algorithm does not need the perturbative expansion with respect to the inflaton fields on super-horizon scale, it works even in highly stochastic cases. For example, when the curvature perturbations are very large or the non-Gaussianities of the curvature perturbations are sizable, the perturbative expansion may break down but our algorithm enables to calculate the curvature perturbations. We apply it to two well-known inflation models, chaotic and hybrid inflation, in this paper. Especially for hybrid inflation, while the potential is very flat around the critical point and the standard perturbative computation is problematic, we successfully calculate the curvature perturbations.
Curvature Perturbations from Higgs Modulated Reheating
School of Physics, Sun Yat-Sen University（中山大学物理学院）；Asia Pacific Center for Theoretical Physics（亚太理论物理中心）；Center for Theoretical Physics, Henan Normal University（河南师范大学理论物理中心）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）
$δn$ formalism: A new formulation for the probability density of the curvature perturbation
Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；Center for High Energy Physics, Peking University（北京大学高能物理中心）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo（东京大学宇宙物质结构宇宙学前沿研究机构（WPI））；Asia Pacific Center for Theoretical Physics (APCTP)（亚太理论物理中心）；Yukawa Institute for Theoretical Physics, Kyoto University（京都大学汤川理论物理研究所）；Leung Center for Cosmology and Particle Astrophysics, National Taiwan University（国立台湾大学梁林杰宇宙学与粒子天体物理研究中心）
Nonperturbative stochastic inflation in perturbative dynamical background
Institute of Theoretical Physics, Chinese Academy of Sciences (CAS)（中国科学院理论物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Asia Pacific Center for Theoretical Physics (APCTP)（亚太理论物理中心）
